Generally, Liquid Crystal Displays (LCDs) include two display substrates where an electric field applying electrode is displayed, and a liquid crystal layer that has dielectric anisotropy and is disposed between the two substrates. LCDs apply a voltage to an electric field applying electrode to generate an electric field in a liquid crystal layer, change the voltage to adjust intensity of the electric field, and thus adjust a transmittance of light passing through the liquid crystal layer, thereby displaying a desired image.
Since LCDs cannot self emit light, the LCDs require a separate light source called a backlight, and the light source is being replaced by Light Emitting Diodes (LEDs).
Since LEDs are semiconductor devices, LEDs have long service life, fast lighting speed, low consumption power, and excellent color reproductivity. Moreover, LEDs are robust to impact, and facilitate the miniaturizing and thinning of LEDs. Therefore, a backlight using LEDs are being mounted on medium and large LCDs such as computer monitors and televisions (TVs), in addition to small LCDs mounted on mobile phones, etc.